Apparatus and method for a beam-directing system using a gated light valve

ABSTRACT

In one embodiment, an apparatus includes a first stage and a second stage. The first stage may include a micro light-directing unit that is operable to receive a light beam from a light source and direct the light beam along one dimension to discrete input locations of a second stage. The second stage may be operable to receive the light beam from the first stage at the discrete input locations along the one dimension and direct the light beam through two dimensions to discrete output locations of the second stage to scan a three-dimensional space.

PRIORITY

This application is a continuation under 35 U.S.C. § 120 of U.S. patentapplication Ser. No. 15/858,284, filed Dec. 29, 2017, which isincorporated herein by reference.

BACKGROUND

Light Detection and Ranging (LIDAR) is a sensing method that uses alight beam to measure the distance to various objects. A LIDARinstrument works by emitting a light beam out into the world andmeasuring the time it takes to return. The return time for each returnlight beam is combined with the location of the LIDAR instrument todetermine a precise location of a surface point of an object. Thislocation is recorded as a three-dimensional point in space, i.e.,azimuth, elevation, and range. In some lidars, the Doppler informationfrom the target is acquired, providing a 4D data point. Several recordedthree-dimensional points may provide an accurate three-dimensionalrepresentation of the environment surrounding the LIDAR instrument. Thisthree-dimensional representation may be referred to as a point cloud. ALIDAR system typically includes a light source, a receiver, a mirrorthat rotates or tilts on a gimbal, timing electronics, a GlobalPositioning System (GPS), and an Inertial Measurement Unit (IMU).Traditional LIDAR systems may be slower and have lower resolution thanwhat is needed for at least some autonomous vehicle applications. Also,traditional LIDAR systems may be prone to drift and calibration errorscaused by vibrations inherent in vehicular movement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example grated light valve (GLV).

FIG. 1B illustrates another view of an example GLV.

FIG. 2 illustrates a cross-section of a GLV depicting an example pathfor diffracted light.

FIG. 3 illustrates another example diagram for directing light using anexample GLV.

FIG. 4 illustrates an example beam-directing system that uses a GLV inconjunction with a rotating mirror to direct light in athree-dimensional space.

FIG. 5 illustrates an example beam-directing system that uses a GLV inconjunction with a fiber bundle and receiving antenna to direct light ina three-dimensional space.

FIG. 6A illustrates an example beam-directing system that uses a GLV inconjunction with a fiber bundle to direct light in a three-dimensionalspace.

FIG. 6B illustrates an example fiber bundle cross-section.

FIG. 7 illustrates an example beam-directing system installed in anexample autonomous vehicle.

FIG. 8 illustrates an example of a computing system.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Traditional LIDAR systems may use a mechanical gimbal and a mirror tosteer light beams into space. In a traditional LIDAR system, light isemitted from a light source toward a mirror that can rotate in 360° andreflect the light pulses in several directions around the LIDARinstrument. Such LIDAR instruments are bulky, slow, susceptible tothermal and vibrational drift, and provide a lower resolution than whatmay be needed for precise object recognition and imaging. As an exampleand not by way of limitation, when a traditional LIDAR instrument ismounted onto an autonomous vehicle, the motion of the vehicle along withwide-ranging temperature differences that can occur in a single day maycause the gimbal and mirror arrangement to deform and lose accuracy overtime. This may require the LIDAR instrument to be repaired,recalibrated, or even replaced, which may be costly and aggravating toconsumers.

In particular embodiments, a beam-directing system may use amicro-electromechanical system (MEMS) device called a grated light valve(GLV) and the principle of light diffraction to direct a light beam in atwo-dimensional space. The beam-directing system may have two stages.The first stage may include a light source that emits a light beam ontoa GLV. The GLV may direct the light beam along one dimension to discreteinput locations of a second stage. The second stage may include amechanism whereby the input light beam is directed through twodimensions to discrete output locations. This may enable thebeam-directing system to scan a three-dimensional space without the useof a gimbaled mirror. In particular embodiments, the mechanism thatdirects the light beam through two dimensions may be a bundle offiber-optic cables whose input ends are located at the discrete inputlocations and whose output ends may be pointed in several differentdirections.

The beam-directing system may have several advantages over traditionalLIDAR systems. The beam-directing system requires very few moving parts,which may create a more robust sensing system and reduce or eliminatethe need for maintenance or replacement of system components. Also,because particular embodiments of the beam-directing system do notrequire the rotation or tilting of cumbersome mirrors, thebeam-directing system may be able to scan faster than traditional LIDARsystems and thus sense nearby objects more quickly or provide a higherrefresh rate.

In the following description, various embodiments will be described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will also be apparent to one skilled in the art that theembodiments may be practiced without the specific details. Furthermore,well-known features may be omitted or simplified in order not to obscurethe embodiment being described. In addition, the embodiments disclosedherein are only examples, and the scope of this disclosure is notlimited to them. Particular embodiments may include all, some, or noneof the components, elements, features, functions, operations, or stepsof the embodiments disclosed above. Embodiments according to theinvention are in particular disclosed in the attached claims directed toa method, a storage medium, a system and a computer program product,wherein any feature mentioned in one claim category, e.g., method, canbe claimed in another claim category, e.g., system, as well. Thedependencies or references back in the attached claims are chosen forformal reasons only. However any subject matter resulting from adeliberate reference back to any previous claims (in particular multipledependencies) can be claimed as well, so that any combination of claimsand the features thereof are disclosed and can be claimed regardless ofthe dependencies chosen in the attached claims. The subject-matter whichcan be claimed comprises not only the combinations of features as setout in the attached claims but also any other combination of features inthe claims, wherein each feature mentioned in the claims can be combinedwith any other feature or combination of other features in the claims.Furthermore, any of the embodiments and features described or depictedherein can be claimed in a separate claim and/or in any combination withany embodiment or feature described or depicted herein or with any ofthe features of the attached claims.

FIGS. 1A and 1B illustrate an example grated light valve (GLV). A GLVmay operate by using an adjustable diffraction grating. A GLV may beconstructed on a silicon wafer (e.g., common plane 140) and may includeseveral parallel rows of reflective micro-ribbons suspended above an airgap. A group of ribbons arranged on a substrate may be referred to as a“pixel.” A given GLV pixel 110 may include several bias ribbons 120 andseveral active ribbons 130. The bias ribbons and the active ribbons maybe arranged such that every other ribbon is an active ribbon that can bedepressed slightly by applying a voltage between the ribbons and a baseconductor. The voltage may create an electric field that causes theactive ribbons to deflect downward toward the common plane 140 while thebias ribbons remain stationary. This deflection of every other ribboncreates a square-well diffraction grating between each bias ribbon 120and each active ribbon 130. A square-well diffraction grating diffractslight into fixed diffraction angles. The depth of the square-welldiffraction grating depends on how far the active ribbons 130 aredeflected, which in turn depends on the amount of voltage applied to theribbons. When a voltage is applied to alternate ribbons, the GLV is setto a diffraction state. The source light is then diffracted at setangles. When the depth of the square-well diffraction grating is ¼th ofthe light's wavelength, the entire specular beam is converted intodiffracted light that diffracts off the GLV at a specific angle.

FIG. 2 illustrates a cross-section of a GLV pixel depicting an examplepath for diffracted light. A voltage is applied to the active ribbons130 causing them to deflect downward while bias ribbons 120 remainstationary. This configuration may be understood to be the “on” oractivated configuration. As mentioned above, this deflection of everyother ribbon creates a square-well diffraction grating between each biasribbon 120 and each active ribbon 130. Incoming light 210 is impingeddirectly onto the GLV pixel. When light passes through a narrow slit, itis diffracted. The incoming light 210 reflects off the active ribbons,but as the light passes the narrow slit created by the bias ribbons, thelight may be diffracted so that it comes off the GLV pixel at an anglethat is different than the angle at which it impinged on the pixel. Thedistance between the bias ribbons and the active ribbons may be ¼th ofthe light's wavelength so that all of the incoming light may bediffracted. If the depth of the square-well diffraction grating is moreor less than ¼th of the light's wavelength, the intensity of thediffracted light 220 may change. In particular embodiments, the changingangle of diffracted light may be used to direct the beam to a particularpoint. If no voltage is applied to the active ribbons, the surfaces ofthe ribbons may function together as a mirror.

In particular embodiments, when a GLV pixel is activated, the activeribbons are deflected. The resulting square-well diffraction grating mayintroduce phase offsets between the wave fronts of light reflected offthe bias ribbons and the active ribbons. The functional dependence ofthe first-order diffraction lobes is

${I_{1{st}} = {I_{\max}{\sin^{2}\left( \frac{2{\pi d}}{\lambda} \right)}}},$

where I_(max) is the maximum first order diffracted intensity (whered=λ/4), d is the grating depth, and λ is the wavelength of the incominglight. By varying the voltage applied to the active ribbons, it ispossible to control the grating depth at each pixel. Thus, it may bepossible to control the proportion of light that is reflected ordiffracted, as well as the angles of diffraction, which may occur atdiscrete angles.

FIG. 3 illustrates an example diagram for directing light using anexample six-pixel GLV. A stationary light source may direct a light beamat the GLV. In this example drawing, the six arrows pointing from leftto right may represent a single light beam. The example diagram of FIG.3 also includes six discrete locations 1-6 along the top of the figure.By activating different pixels, it is possible to direct the light beamonto any of the six locations. As an example and not by way oflimitation, a controller may activate pixel 4 by applying a voltage tothe active ribbons of that pixel, as discussed above. Pixels 1-3, 5, and6 may be left deactivated. When the light beam impinges on pixel 4, itmay be diffracted at an angle such that it is directed toward location 2along the top of the figure. When the light beam impinges on thedeactivated pixels, the light is simply reflected back like a mirror. Asanother example and not by way of limitation, the controller may directa light beam onto location 5 by activating pixel 2. By activating anddeactivating different pixels, it is possible to direct the light intoany of the six locations. Although the example GLV only has six pixels,this is for illustration purposes only. GLVs typically have between1,024 pixels and 8,192 pixels. Thus, by activating different pixels on a1,024 pixel GLV, it is possible to direct the light beam into 1,024discrete locations. Likewise, by activating different pixels on an 8,192pixel GLV, it is possible to direct the light beam into 8,192 discretelocations. Because voltage is applied to each pixel independently, eachpixel of the GLV operates independently. This may allow for fasttransitions from one location to another, even if the locations are farapart. As an example and not by way of limitation, directing light fromposition 1 to position 2 may take the same amount of time as directinglight from position 1 to position 1,024. This provides an advantage overtraditional LIDAR systems, which require the gimbaled mirror to passthrough every intervening position when transitioning from one positionto another. Another advantage of GLV pixel activation includes theability to change the scan pattern very quickly and without altering themechanical setup of the hardware.

When all but one or relatively few pixels are deactivated, most of thelight beam emitted from light source 401 is lost. This is because onlythe activated pixels direct light to the discrete input locations. Thismeans that all the light that impinges on the deactivated pixels isreflected back toward the light source or to an optical trap. Inparticular embodiments, at any given time, most of the pixels may bedeactivated and thus most of the light may be lost. To save powerconsumption, one of two methods may be used. First, in particularembodiments a dynamic phase array may be used on the GLV. The phase ofthe light wave emitted from the light source may be controlled using anoptical phase array. Controlling the phase of the light wave may enablemost (if not all) of the incoming light beam to be aimed at a particularlocation by means of constructive interference.

Second, instead of completely turning off the inactive pixels, thecontroller may modulate each pixel. In this embodiment, instead oflosing the majority of the power due to deactivated pixels being totally“off,” the controller may modulate each pixel independently of the otherpixels. The controller may assign a unique (e.g., orthogonal) randomsequence to each pixel. Then, at the receiver side, the receiver orother appropriate computing device may separate the received signals bymatched filtering. In other words, the system may transmit a signal byactivating several pixels simultaneously, each transmitting its ownunique random sequence. The receiver may receive this signal (whichincludes light beams from several pixels) and separate each beam byconvolving the received signal between each of the random sequencepatterns. As an example and not by way of limitation, a signal mayinclude a first random sequence from pixel 1 that is “01101” and thesame signal may also include a second random sequence from pixel 2 thatis “11001.” The receiver may receive a return signal that has thesequence “0110111001.” The receiver (or other suitable computing device)may separate this signal into its two pixel-generated light beams:“01101” and “11001.” In particular embodiments, the receiver willreceive a superimposed signal originating from reflections from twoseparate lasers. Due to the orthogonality of the transmit beams, theycan be separated at the receiver. In particular embodiments, theinformation in each light beam may then be collected and processed. Thisrandom modulation may not require any extra hardware. Using this method,at least some extra light generated by light source 401 may be used totransmit information, instead of being wasted.

FIG. 4 illustrates an example beam-directing system 400 that uses a GLV410 in conjunction with a gimbaled mirror 401 to direct light in atwo-dimensional space. A limitation of the GLV described thus far isthat it may only diffract light along one dimension. This may bebeneficial in directing light to discrete points along a one-dimensionalpath, but if it is desired to direct light in two or three dimensions, asecond stage may be added. The beam-directing system may include a firststage 405 and a second stage 406. The first stage may include a lightsource 401, a lens 402, a silver mirror 403, a concave mirror 404, and aGLV 405.

Light source 401 may be any suitable light source used in current LIDARsystems. As an example and not by way of limitation, the light source401 may be a randomly modulated continuous wave laser. A laser such asthis may be suitable because it may transmit light pulses at random,which may enable the light source to transmit one or more light beamsbefore a previously emitted beam is received. Two light beamssimultaneously transmitted with two different random codes may enable acomputing device associated with the beam-directing system 400 todifferentiate between the two light beams. Such a light source bothspeeds up scanning and reduces interference.

Lens 402 may be any suitable lens for spreading a light beam. As anexample and not by way of limitation lens 402 may be a Powell lens,which may emit light that is spread uniformly throughout its associatedfan angle. Other circular or Gaussian lenses may be suitable for thebeam-directing system 400 as well. The silver mirror 403 and concavemirror 404 may be useful for optical beam manipulation. They may enablea shorter optical path so that the entire length of the GLV may beimpinged with light while the dimensions of the first stage ofbeam-directing system 400 remain relatively small. Lens 402, silvermirror 403 and concave mirror 404 may ensure that the light beam isimpinged onto the GLV 410 in a direct and uniform fashion. GLV 410 maydiffract light according to the process described above with regard toFIGS. 2 and 3.

In particular embodiments, a controller may activate the desired pixelof GLV 410 to direct the light beam toward the second stage 406 and ontothe desired input locations 411. In particular embodiments, there may bean equal number of input locations 411 to the number of pixels in theGLV. As an example and not by way of limitation, if the GLV has 1,024pixels, there may be 1,024 input locations. The input locations 411 maybe arranged along a line in one dimension. For example, the line may bealong the surface of the gimbaled mirror 401. Here, the second stage mayinclude the gimbaled mirror 401 and optionally lens 408. Light may bediffracted off GLV 410 at discrete points. These diffracted light beamsmay impinge on the gimbaled mirror along a one-dimensional line. Thegimbaled mirror may then rotate or otherwise tilt in several directionsalong a second dimension to reflect the light beams out into athree-dimensional space surrounding the beam-directing system 400. Inparticular embodiments the gimbaled mirror may tilt perpendicular to theone-dimensional line on which the diffracted light beams are impinged onthe mirror.

As an example and not by way of limitation, the light beams may diffractoff the GLV along a vertical line. In this example, the light beams mayimpinge on the mirror at different locations along a vertical line thatcovers at least part of the surface of the mirror. The mirror may tilthorizontally left and right, which is perpendicular to the verticalline. Thus, the gimbaled mirror 401 may operate as a second stagewhereby it reflects the light beams from the first stage (e.g., GLV 410)and directs the light beams through two dimensions to discrete outputlocations. This may allow the beam-directing system 400 to scan athree-dimensional space. Beam-directing system 400 may also include anoptical trap 421 which may catch the light that reflects off theun-activated pixels of the GLV. Alternatively, an optical trap may notbe provided. An optical trap may be an apparatus that receives the lightthat is diffracted off the GLV but not in the direction of the desiredinput locations 411. Referring to FIGS. 2 and 3, the GLV diffracts lightin two directions. According to particular embodiments described herein,some of the light is diffracted in the direction of a desired inputlocation 411, and some of the light is diffracted away from the desiredinput location (this will be referred to as “stray light beams”). Thisis a natural consequence of using GLVs to steer laser beams. To reducethe likelihood of stray light beams interfering with the LIDAR system,the optical trap may absorb the stray light beams instead of reflectingthem. This may ensure that the only light that leaves the LIDAR systemtravels through the second stage 406.

An advantage of beam-directing system 400 over the other systemsdiscussed below may be the wide availability of a suitable gimbaledmirror. Gimbaled mirrors are often available as an off-the-shelf part,whereas the fiber-optic cable bundles (discussed below) ofbeam-directing system 500 and 600 may require customized positioning.Thus, beam-directing system 400 may be set up and installed more quicklyand affordably than beam-directing systems 500 or 600. If a user is moreconcerned with fast and easy setup than with robustness, scanning speed,or aerodynamics, the user may consider using beam-directing system 400.

FIG. 5 illustrates another example beam-directing system that uses a GLVin conjunction with a fiber bundle to direct light in athree-dimensional space. Beam-directing system 500 may include some ofthe same components as beam-directing system 400 and operate insubstantially the same manner, except that instead of using a gimbaledmirror to direct the beam in two-dimensions, the beam-directing system500 may use transmit fiber-optic cables 512.

In particular embodiments, a controller may activate the desired pixelof GLV 410 to direct the light beam toward the second stage 506 and ontothe desired input locations 511. In particular embodiments, there may bean equal number of input locations 511 to the number of pixels in theGLV. As an example and not by way of limitation, if the GLV has 1,024pixels, there may be 1,024 input locations. The input locations 511 maybe arranged along a line in one dimension. At least some of, and inparticular embodiments, each of the input locations 511 may be coupledto a transmit fiber-optic cable 512. Even though only four transmitfiber-optic cables are illustrated as being coupled to the inputlocations 511, this is to simplify the drawings and allow space foradequate notation. This disclosure contemplates a GLV with any number ofpixels, a second stage with any number of corresponding input locations,and a fiber bundle with any number of corresponding fiber-optic cablescoupled to a different input location. For example, the first stage GLVmay have 1,024 up to 8,192 pixels, the second stage may have from 1,024up to 8,192 input locations 511, and a fiber bundle may have from 1,024up to 8,192 fiber-optic cables that are each coupled to a differentinput location.

The transmit fiber-optic cable 512 may have a transmit-input end(coupled to one of the input locations 511) and a transmit-output end,which may emit the beam into the environment that surrounds thebeam-directing system 500. Lens 408 may act to spread the emitted lightbeams into a wider space. Each transmit fiber-optic cable 512 may bepart of a fiber bundle 507. Each transmit-output end of a transmitfiber-optic cables 512 may be positioned in any suitable direction. Incontrast to the arrangement of transmit-input ends, the transmit-outputends need not all be facing in the same direction. As an example and notby way of limitation, a first transmit-output end may be directed to theleft, away from the GLV, and a second transmit-output end may bedirected in the opposite direction, pointed toward the right. Byarranging each transmit-output end in a different direction, it may bepossible to emit light beams in e.g., 1,024 discrete directions in atwo-dimensional (or three-dimensional) space. In particular embodiments,the light beams may be directed in a 360° area around the beam-directingsystem 600 without requiring a gimbaled mirror. Indeed, the only movingparts in the entire beam-directing system 400 may be the microscopicdeflection of active ribbons 130 when a voltage is applied to the pixel.Thus, the transmit fiber-optic cables 612 may operate as a second stagewhereby they receive the light beams from the first stage (e.g., GLV410) and direct the light beams through two (or three) dimensions todiscrete output locations. This may allow the beam-steering system 500to scan a two- or three-dimensional space with fewer moving parts thantraditional LIDAR systems. Very few or no moving parts on thetransmit-side in the LIDAR scanning system creates a more robust sensingsystem and reduces the need for maintenance or replacement of systemcomponents. Also, a LIDAR scanning system that does not require therotation or tilting of cumbersome mirrors allows for faster scanningthan traditional LIDAR systems. Fast scanning may enable the system tosense nearby objects more quickly or provide a higher refresh rate.

In beam-directing system 500, receiving the return light beams may beaccomplished by a receiver 509 which may share many of the samecomponents as receiver 409 from FIG. 4. Comparing to FIG. 6A, one maindifference may be that receiver 509 includes receiving antenna 510,whereas in FIG. 6A, reception is accomplished through receivefiber-optic cables 613. Receiver 509 and receiving antenna 510 may havethe advantage of easier installation on existing vehicles, because itmay be more difficult and time-consuming to install receive fiber-opticcables (e.g., 613 in FIG. 6A) than a receiving antenna 510. Receivefiber-optic cables (e.g., 613 in FIG. 6A) may have the advantage ofhelping the car to be more sleek and aerodynamic, because thefiber-optic cables need only extend to the surface of the vehicle (asillustrated in FIG. 7). This may save on energy costs, may also protectthe LIDAR system since no pieces are outside the vehicle like they arein traditional LIDAR systems. The transmit fiber-optic cables (e.g., 612in FIG. 6A) may be arranged in in such a way as to ensure evendistribution of emitted light beams. This disclosure contemplates anysuitable arrangement of transmit fiber-optic cables (e.g., 613 in FIG.6A).

Although several components are shown in FIG. 5, not all components maybe necessary for operation of the beam-directing system 500. As anexample and not by way of limitation, lens 402, silver mirror 403,concave mirror 404, and lens 408 may be removed without defeating theessential functioning of beam-directing system 500. The requiredcomponents for beam-directing system 400 to operate properly may belight source 401, receiver 509, antenna 510, GLV 410, and the transmitfiber-optic cables 512.

FIG. 6A illustrates an example beam-directing system 600 that uses a GLVin conjunction with a fiber bundle to direct light in a two- orthree-dimensional space. Beam-directing system 600 may differ frombeam-directing system 500 in that instead of using a receiving antenna510 to collect the return light beams, beam-directing system 600 may usereceive fiber-optic cables 613. These may serve a similar purpose as areceiving antenna (e.g., capturing return light signals), but may bestructurally different in that they are fiber-optic cables and not areceiving antenna. Also, the receive ends of the receive fiber-opticcables may extend no farther than the surface of the vehicle and mayrequire no moving parts.

Transmission of LIDAR signals may operate like the transmission of LIDARsignals in beam-directing system 500 and may have the same transmissionadvantages as beam-steering system 500. Beam-steering system 600 mayinclude fiber bundle 607. Fiber bundle 607 may include both the transmitfiber-optic cables 612 as well as several receive fiber-optic cables613. The receive fiber-optic cables 613 may receive the return lightbeams after they have been transmitted through transmit fiber-opticcables 612 and reflected off an object in the external environment. Thereceive fiber-optic cables 613 may replace the traditional LIDARreceiver antenna (e.g., receiving antenna 510). Although not illustratedin FIG. 6A, beam-directing system 600 may also include an optical trappositioned near GLV 410 such that it may catch the light that reflectsoff the un-activated pixels of the GLV.

Beam-directing system 600 further reduces the number of componentstypically included in a traditional LIDAR system. The beam-directingsystem may have several advantages over traditional LIDAR systems. Thebeam-directing system requires very few moving parts, which may create amore robust sensing system and reduce or eliminate the need formaintenance or replacement of system components. Also, becauseparticular embodiments of the beam-directing system do not require therotation or tilting of cumbersome mirrors, the beam-directing system maybe able to scan faster than traditional LIDAR systems and thus sensenearby objects more quickly or provide a higher refresh rate.Additionally, the transmit and receive fiber-optic cables remove theneed to have system components mounted outside the vehicle. This maycreate a more aerodynamic vehicle that saves energy through a reductionin wind resistance.

Although several components are shown in FIGS. 6A and 6B, not allcomponents may be necessary for operation of the beam-directing system600. As an example and not by way of limitation, lens 402, silver mirror403, concave mirror 404, and lens 408 may be removed without defeatingthe essential functioning of light-directing system 600. The requiredcomponents for light-directing system 600 to operate properly may belight source 401, receiver 409, GLV 410, and the transmit and receivefiber-optic cables 612 and 613 along with their respectivetransmit-input and transmit-output ends and receive-input andreceive-output ends, where the transmit-input ends are coupled at inputlocations 611 and the transmit-output ends and receive-input ends arearranged in directions suitable for sensing at least part of theenvironment surrounding the beam-directing system 600. The receiveoutput ends of receive fiber-optic cables 613 may be coupled to receiver409, as illustrated in FIG. 6A.

FIG. 6B illustrates an example fiber bundle cross-section. The transmitfiber-optic cables 612 may be interspersed with the receive fiber-opticcables 613. It may generally be desirable to arrange the transmitfiber-optic cables 612 and receive fiber-optic cables 613 in such a wayas to ensure even distribution of emitted light beams as well as toensure that a sufficient number of return light beams are received bythe receive fiber-optic cables 613. Although a particular arrangement oftransmit fiber-optic cables 612 and receive fiber-optic cables 613 isillustrated in FIG. 6B, this disclosure contemplates any suitablearrangement of transmit fiber-optic cables 612 and receive fiber-opticcables 613.

FIG. 7 illustrates an example beam-directing system installed in anexample autonomous vehicle 710. This beam-directing system may besimilar to beam-directing systems 600 and may include a light source andGLV unit 720 that is located somewhere in the interior of autonomousvehicle 710. GLV unit 720 may include the components of the first stage405 of FIGS. 4 and 5. As examples and not by way of limitation, thelight source and GLV unit 720 may be positioned beneath one of thepassenger seats, in the trunk of the autonomous vehicle, on the roof, orin any other suitable location. This beam-directing system may alsoinclude fiber-optic cables 730 which may be transmit fiber-optic cables,receive fiber-optic cables, or both. Their respective transmit-outputends and receive-input ends may run along the interior of the vehicletoward points 731, 732, and 733.

An advantage of beam-directing systems 400 and 500 is that the lightsource and GLV components (e.g., element 720) may be located in adifferent location in the autonomous vehicle than the transmit-outputends and receive-input ends of the transmit and receive fiber-opticcables. These locations may be remote from each other. Another advantageis the possibility of utilizing only one laser source and GLV to drivethe numerous fiber-coupled antennas distributed around the vehicle. Asexamples and not by way of limitation, fiber optic cables 730 areillustrated in FIG. 7 as running along the interior of the autonomousvehicle toward several exterior surfaces of the vehicle. Elements 731,732, and 733 may correspond to the transmit-output ends of thefiber-optic cables, the receive-input ends of the fiber-optic cables, orboth. In particular embodiments, element 730 may correspond tosub-bundles of fiber-optic cables that comprise several fiber-opticcables. As an example and not by way of limitation, the GLV may have1,024 pixels. A separate fiber optic cable may be coupled to each of the1,024 possible input locations, giving the beam-directing system 1,024fiber optic cables. Those fiber optic cables may be arranged in anysuitable manner. As an example and not by way of limitation, 341fiber-optic cables may run from the light source and GLV unit 720 towardthe front of the autonomous vehicle at point 731, 341 fiber-optic cablesmay run toward the top of the autonomous vehicle at point 732, and 342fiber-optic cables may run toward the back of the autonomous vehicle atpoint 733. The transmit-output ends and the receive-input ends of thefiber-optic cables may be fanned out at points 731, 732, 733, orotherwise arranged to scan a suitable amount of the external environmentsurrounding the autonomous vehicle. Although not illustrated in FIG. 7,this disclosure contemplates an autonomous vehicle 710 equipped withfiber-optic cables that emerge from the surface of the autonomousvehicle at any suitable location, including the front and rear bumpers,the side doors, the hubs, the wheels, the undercarriage of theautonomous vehicle, or any other suitable location. Moreover, althoughonly one beam-directing system is illustrated as being installed inautonomous vehicle 710, this disclosure contemplates an autonomousvehicle having any suitable number of beam-directing systems.

In particular embodiments, a beam-directing system may use planar lightvalve technology (PLV) instead of a GLV. A PLV may be a two-dimensionalanalog of the GLV. In a PLV, pixels may be arranged in atwo-dimensional, close-packed array. A PLV system may be able tomodulate the amplitude or the phase of a light beam, or both theamplitude and phase simultaneously. A pixel of a PLV may include asquare piston array. As an example and not by way of limitation, a pixelmay include a 2×2 piston array. In contrast to the ribbons in a GLVwhich are thin, elongated mirrors, the pistons in a PLV may bereflective squares. The pistons may be controlled in a similar manner asthe ribbons on the GLV. By applying a voltage to diagonally oppositepistons, a controller can cause the diagonally opposite pistons todeflect by ¼th the light's wavelength. Because the pistons are 2D andare laid out in a 2D fashion (as opposed to being 1D ribbons),diffracted light is emitted in two dimensions, rather than onedimension. Using a PLV in place of a GLV may reduce the need for asecond stage (e.g., fiber bundle or gimbaled mirror) to direct the lightinto two or three dimensions. An advantage of a PLV is that PLVs providea higher optical etendue than the other systems discussed herein.

FIG. 8 illustrates an example computer system 800. In particularembodiments, one or more computer systems 800 perform one or more stepsof one or more methods described or illustrated herein. In particularembodiments, one or more computer systems 800 provide functionalitydescribed or illustrated herein. In particular embodiments, softwarerunning on one or more computer systems 800 performs one or more stepsof one or more methods described or illustrated herein or providesfunctionality described or illustrated herein. Particular embodimentsinclude one or more portions of one or more computer systems 800.Herein, reference to a computer system may encompass a computing device,and vice versa, where appropriate. Moreover, reference to a computersystem may encompass one or more computer systems, where appropriate.

This disclosure contemplates any suitable number of computer systems800. This disclosure contemplates computer system 800 taking anysuitable physical form. As example and not by way of limitation,computer system 800 may be an embedded computer system, a system-on-chip(SOC), a single-board computer system (SBC) (such as, for example, acomputer-on-module (COM) or system-on-module (SOM)), a desktop computersystem, a laptop or notebook computer system, an interactive kiosk, amainframe, a mesh of computer systems, a mobile telephone, a personaldigital assistant (PDA), a server, a tablet computer system, anaugmented/virtual reality device, or a combination of two or more ofthese. Where appropriate, computer system 800 may include one or morecomputer systems 800; be unitary or distributed; span multiplelocations; span multiple machines; span multiple data centers; or residein a cloud, which may include one or more cloud components in one ormore networks. Where appropriate, one or more computer systems 800 mayperform without substantial spatial or temporal limitation one or moresteps of one or more methods described or illustrated herein. As anexample and not by way of limitation, one or more computer systems 800may perform in real time or in batch mode one or more steps of one ormore methods described or illustrated herein. One or more computersystems 800 may perform at different times or at different locations oneor more steps of one or more methods described or illustrated herein,where appropriate.

In particular embodiments, computer system 800 includes a processor 802,memory 804, storage 806, an input/output (I/O) interface 808, acommunication interface 810, and a bus 812. Although this disclosuredescribes and illustrates a particular computer system having aparticular number of particular components in a particular arrangement,this disclosure contemplates any suitable computer system having anysuitable number of any suitable components in any suitable arrangement.

In particular embodiments, processor 802 includes hardware for executinginstructions, such as those making up a computer program. As an exampleand not by way of limitation, to execute instructions, processor 802 mayretrieve (or fetch) the instructions from an internal register, aninternal cache, memory 804, or storage 806; decode and execute them; andthen write one or more results to an internal register, an internalcache, memory 804, or storage 806. In particular embodiments, processor802 may include one or more internal caches for data, instructions, oraddresses. This disclosure contemplates processor 802 including anysuitable number of any suitable internal caches, where appropriate. Asan example and not by way of limitation, processor 802 may include oneor more instruction caches, one or more data caches, and one or moretranslation lookaside buffers (TLBs). Instructions in the instructioncaches may be copies of instructions in memory 804 or storage 806, andthe instruction caches may speed up retrieval of those instructions byprocessor 802. Data in the data caches may be copies of data in memory804 or storage 806 for instructions executing at processor 802 tooperate on; the results of previous instructions executed at processor802 for access by subsequent instructions executing at processor 802 orfor writing to memory 804 or storage 806; or other suitable data. Thedata caches may speed up read or write operations by processor 802. TheTLBs may speed up virtual-address translation for processor 802. Inparticular embodiments, processor 802 may include one or more internalregisters for data, instructions, or addresses. This disclosurecontemplates processor 802 including any suitable number of any suitableinternal registers, where appropriate. Where appropriate, processor 802may include one or more arithmetic logic units (ALUs); be a multi-coreprocessor; or include one or more processors 802. Although thisdisclosure describes and illustrates a particular processor, thisdisclosure contemplates any suitable processor.

In particular embodiments, memory 804 includes main memory for storinginstructions for processor 802 to execute or data for processor 802 tooperate on. As an example and not by way of limitation, computer system800 may load instructions from storage 806 or another source (such as,for example, another computer system 800) to memory 804. Processor 802may then load the instructions from memory 804 to an internal registeror internal cache. To execute the instructions, processor 802 mayretrieve the instructions from the internal register or internal cacheand decode them. During or after execution of the instructions,processor 802 may write one or more results (which may be intermediateor final results) to the internal register or internal cache. Processor802 may then write one or more of those results to memory 804. Inparticular embodiments, processor 802 executes only instructions in oneor more internal registers or internal caches or in memory 804 (asopposed to storage 806 or elsewhere) and operates only on data in one ormore internal registers or internal caches or in memory 804 (as opposedto storage 806 or elsewhere). One or more memory buses (which may eachinclude an address bus and a data bus) may couple processor 802 tomemory 804. Bus 812 may include one or more memory buses, as describedin further detail below. In particular embodiments, one or more memorymanagement units (MMUs) reside between processor 802 and memory 804 andfacilitate accesses to memory 804 requested by processor 802. Inparticular embodiments, memory 804 includes random access memory (RAM).This RAM may be volatile memory, where appropriate. Where appropriate,this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, whereappropriate, this RAM may be single-ported or multi-ported RAM. Thisdisclosure contemplates any suitable RAM. Memory 804 may include one ormore memories 804, where appropriate. Although this disclosure describesand illustrates particular memory, this disclosure contemplates anysuitable memory.

In particular embodiments, storage 806 includes mass storage for data orinstructions. As an example and not by way of limitation, storage 806may include a hard disk drive (HDD), a floppy disk drive, flash memory,an optical disc, a magneto-optical disc, magnetic tape, or a UniversalSerial Bus (USB) drive or a combination of two or more of these. Storage806 may include removable or non-removable (or fixed) media, whereappropriate. Storage 806 may be internal or external to computer system800, where appropriate. In particular embodiments, storage 806 isnon-volatile, solid-state memory. In particular embodiments, storage 806includes read-only memory (ROM). Where appropriate, this ROM may bemask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM),or flash memory or a combination of two or more of these. Thisdisclosure contemplates mass storage 806 taking any suitable physicalform. Storage 806 may include one or more storage control unitsfacilitating communication between processor 802 and storage 806, whereappropriate. Where appropriate, storage 806 may include one or morestorages 806. Although this disclosure describes and illustratesparticular storage, this disclosure contemplates any suitable storage.

In particular embodiments, I/O interface 808 includes hardware,software, or both, providing one or more interfaces for communicationbetween computer system 800 and one or more I/O devices. Computer system800 may include one or more of these I/O devices, where appropriate. Oneor more of these I/O devices may enable communication between a personand computer system 800. As an example and not by way of limitation, anI/O device may include a keyboard, keypad, microphone, monitor, mouse,printer, scanner, speaker, still camera, stylus, tablet, touch screen,trackball, video camera, another suitable I/O device or a combination oftwo or more of these. An I/O device may include one or more sensors.This disclosure contemplates any suitable I/O devices and any suitableI/O interfaces 808 for them. Where appropriate, I/O interface 808 mayinclude one or more device or software drivers enabling processor 802 todrive one or more of these I/O devices. I/O interface 808 may includeone or more I/O interfaces 808, where appropriate. Although thisdisclosure describes and illustrates a particular I/O interface, thisdisclosure contemplates any suitable I/O interface.

In particular embodiments, communication interface 810 includeshardware, software, or both providing one or more interfaces forcommunication (such as, for example, packet-based communication) betweencomputer system 800 and one or more other computer systems 800 or one ormore networks. As an example and not by way of limitation, communicationinterface 810 may include a network interface controller (NIC) ornetwork adapter for communicating with an Ethernet or other wire-basednetwork or a wireless NIC (WNIC) or wireless adapter for communicatingwith a wireless network, such as a WI-FI network. This disclosurecontemplates any suitable network and any suitable communicationinterface 810 for it. As an example and not by way of limitation,computer system 800 may communicate with an ad hoc network, a personalarea network (PAN), a local area network (LAN), a wide area network(WAN), a metropolitan area network (MAN), or one or more portions of theInternet or a combination of two or more of these. One or more portionsof one or more of these networks may be wired or wireless. As anexample, computer system 800 may communicate with a wireless PAN (WPAN)(such as, for example, a Bluetooth WPAN), a WI-FI network, a WI-MAXnetwork, a cellular telephone network (such as, for example, a GlobalSystem for Mobile Communications (GSM) network), or other suitablewireless network or a combination of two or more of these. Computersystem 800 may include any suitable communication interface 810 for anyof these networks, where appropriate. Communication interface 810 mayinclude one or more communication interfaces 810, where appropriate.Although this disclosure describes and illustrates a particularcommunication interface, this disclosure contemplates any suitablecommunication interface.

In particular embodiments, bus 812 includes hardware, software, or bothcoupling components of computer system 800 to each other. As an exampleand not by way of limitation, bus 812 may include an AcceleratedGraphics Port (AGP) or other graphics bus, an Enhanced Industry StandardArchitecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT)interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBANDinterconnect, a low-pin-count (LPC) bus, a memory bus, a Micro ChannelArchitecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, aPCI-Express (PCIe) bus, a serial advanced technology attachment (SATA)bus, a Video Electronics Standards Association local (VLB) bus, oranother suitable bus or a combination of two or more of these. Bus 812may include one or more buses 812, where appropriate. Although thisdisclosure describes and illustrates a particular bus, this disclosurecontemplates any suitable bus or interconnect.

Herein, a computer-readable non-transitory storage medium or media mayinclude one or more semiconductor-based or other integrated circuits(ICs) (such, as for example, field-programmable gate arrays (FPGAs) orapplication-specific ICs (ASICs)), hard disk drives (HDDs), hybrid harddrives (HHDs), optical discs, optical disc drives (ODDs),magneto-optical discs, magneto-optical drives, floppy diskettes, floppydisk drives (FDDs), magnetic tapes, solid-state drives (SSDs),RAM-drives, SECURE DIGITAL cards or drives, any other suitablecomputer-readable non-transitory storage media, or any suitablecombination of two or more of these, where appropriate. Acomputer-readable non-transitory storage medium may be volatile,non-volatile, or a combination of volatile and non-volatile, whereappropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,feature, functions, operations, or steps, any of these embodiments mayinclude any combination or permutation of any of the components,elements, features, functions, operations, or steps described orillustrated anywhere herein that a person having ordinary skill in theart would comprehend. Furthermore, reference in the appended claims toan apparatus or system or a component of an apparatus or system beingadapted to, arranged to, capable of, configured to, enabled to, operableto, or operative to perform a particular function encompasses thatapparatus, system, component, whether or not it or that particularfunction is activated, turned on, or unlocked, as long as thatapparatus, system, or component is so adapted, arranged, capable,configured, enabled, operable, or operative. Additionally, although thisdisclosure describes or illustrates particular embodiments as providingparticular advantages, particular embodiments may provide none, some, orall of these advantages.

What is claimed is:
 1. An apparatus comprising: a first stage thatcomprises a grated-light valve (GLV) that is operable to: receive alight beam from a light source; and direct the light beam along onedimension to discrete input locations of a second stage; and the secondstage, operable to: receive the light beam from the first stage at thediscrete input locations along the one dimension; and direct the lightbeam through two dimensions to discrete output locations of the secondstage to scan a three-dimensional space.
 2. The apparatus of claim 1,wherein the second stage is a fiber-optic bundle comprising a pluralityof transmit fiber-optic cables, each transmit fiber-optic cablecomprising a transmit-input end and a transmit-output end, wherein: thetransmit-input end of each transmit fiber-optic cable is positioned atone of the discrete input locations; and the transmit-output end of eachtransmit fiber-optic cable is operable to direct the light beam towardone of the discrete output locations.
 3. The apparatus of claim 2,wherein the fiber-optic bundle further comprises a plurality of receivefiber-optic cables, each receive fiber-optic cable comprising areceive-input end and a receive-output end, wherein: the receive-inputend of each receive fiber-optic cable is operable to receive a reflectedbeam from one or more locations in the three-dimensional space; and thereceive-output end of each fiber-optic cable is coupled to a receiver.4. The apparatus of claim 1, wherein the second stage is a gimbaledmirror that is operable to tilt perpendicular to the one dimension ofthe discrete input locations.
 5. The apparatus of claim 1, wherein thefirst stage further comprises a dynamic phase array that is operable tocontrol a phase of a light wave emitted from the light source.
 6. Theapparatus of claim 1, wherein: the first stage is positioned at a firstlocation inside an autonomous vehicle; and the second stage comprises aplurality of transmit-input ends and a plurality of transmit-outputends, wherein each transmit-output end is positioned at one of aplurality of second locations inside the autonomous vehicle remote fromthe first location.
 7. A method comprising: at a first stage thatcomprises a grated-light valve (GLV): receiving a light beam from alight source; and directing the light beam along one dimension todiscrete input locations of a second stage; and at the second stage:receiving the light beam from the first stage at the discrete inputlocations along the one dimension; and directing the light beam throughtwo dimensions to discrete output locations of the second stage to scana three-dimensional space.
 8. The method of claim 7, wherein the secondstage is a fiber-optic bundle that comprises a plurality of transmitfiber-optic cables, each transmit fiber-optic cable comprising atransmit-input end and a transmit-output end, wherein: thetransmit-input end of each transmit fiber-optic cable is positioned atone of the discrete input locations; and the transmit-output end of eachtransmit fiber-optic cable points toward one of the discrete outputlocations.
 9. The method of claim 8, wherein the fiber-optic bundlefurther comprises a plurality of receive fiber-optic cables, eachreceive fiber-optic cable comprising a receive-input end and areceive-output end, wherein: the receive-input end of each receivefiber-optic cable points towards a different location in thethree-dimensional space; and the receive-output end of each fiber-opticcable is coupled to a receiver.
 10. The method of claim 1, wherein thesecond stage is a gimbaled mirror that is operable to tilt perpendicularto the one dimension of the discrete input locations.
 11. The method ofclaim 1, wherein the first stage further comprises a dynamic phase arraythat is operable to control a phase of a light wave emitted from thelight source.
 12. The method of claim 1, wherein the first stage ispositioned at a first location inside an autonomous vehicle, and thesecond stage is positioned at one or more second locations inside theautonomous vehicle remote from the first location.
 13. An apparatuscomprising: means for receiving at a first stage a light beam from alight source; means for directing the light beam along one dimension todiscrete input locations of a second stage; means for receiving thelight beam from the first stage at the discrete input locations alongthe one dimension; and means for directing the light beam through twodimensions to discrete output locations of the second stage to scan athree-dimensional space.
 14. The apparatus of claim 13, wherein thesecond stage is a fiber-optic bundle comprising a plurality of transmitfiber-optic cables, each transmit fiber-optic cable comprising atransmit-input end and a transmit-output end, wherein: thetransmit-input end of each transmit fiber-optic cable is positioned atone of the discrete input locations; and the transmit-output end of eachtransmit fiber-optic cable is operable to direct the light beam towardone of the discrete output locations.
 15. The apparatus of claim 14,wherein the fiber-optic bundle further comprises a plurality of receivefiber-optic cables, each receive fiber-optic cable comprising areceive-input end and a receive-output end, wherein: the receive-inputend of each receive fiber-optic cable is operable to receive a reflectedbeam from one or more locations in the three-dimensional space; and thereceive-output end of each fiber-optic cable is coupled to a receiver.16. The apparatus of claim 13, wherein the second stage is a gimbaledmirror that is operable to tilt perpendicular to the one dimension ofthe discrete input locations.
 17. The apparatus of claim 13, wherein thefirst stage further comprises a dynamic phase array that is operable tocontrol a phase of a light wave emitted from the light source.
 18. Theapparatus of claim 13, wherein: the first stage is positioned at a firstlocation inside an autonomous vehicle; and the second stage comprises aplurality of transmit-input ends and a plurality of transmit-outputends, wherein each transmit-output end is positioned at one of aplurality of second locations inside the autonomous vehicle remote fromthe first location.